Benthic foraminifera as palaeoenvironmental indicators during the last million years in the eastern Mediterranean inner shelf

摘要

Benthic and planktonic foraminifera were studied in inner shelf sedimentary sequences in Haifa Bay, Israel. Three boreholes, taken at water depths from 5 to 14. m, spanning about the last 1. Ma, and a set of modern sediment samples used as modern analogue, were utilized for reconstructing palaeoenvironments and palaeobathymetry. The palaeoenvironmental data were used for assessing tectonic activity of the Carmel Fault, a branch of the Dead Sea transform that bounds the southern side of the bay. Quantitative analyses showed four biofacies: a fresh to brackish wetland environment, and three progressively deepening marine biofacies. Relative water depth ranges were estimated using changes in benthic foraminiferal assemblages, presence or absence of Ammonia sp. 1, and the percentage of planktonic foraminifera.The distribution of the biofacies suggests water depths no deeper than 15. m during most interglacial stages, water depths to 15-40. m during short transgressive phases of MIS 5.5, 7, 11 and 13, and water depth reaching 40-80. m in the earliest transgressive phases (MIS 27? and MIS 29?). The environmental conditions on both sides of the fault were quite similar along the succession. This suggests that the movements of the uplifted and down-faulted blocks have more or less coincided since about 1. Ma.